The exams are only available to view for a set amount of time after you take them. You should print them out or save them to your computer so you always have them available. Also save, print, or make note of the correct answers to the exam questions. You can use them as kind of a study guide for your proctor exams.
What I do for every class is as soon as it's open I save the study guide, syllabus, exams, any assignments or project instructions and the links to recorded lectures to my computer (and a backup flash drive). That way I have them even after I finish the class and can print anything I need to. I do this before I even start the lessons so I don't forget.